Fix the extended integrity checks in the liberasurecode decode function.  Previously, it was failing if the number of invalid fragments was k or greater, which is incorrect.
Fix the extended integrity checks in the liberasurecode decode
function.  Previously, it was failing if the number of invalid
fragments was k or greater, which is incorrect.

We should only be able to decode if:

  (num given fragments - num invalid fragments) >= k

This means fail if:

  (num given fragments - num invalid fragments) < k

cedricde/liberasurecode,tsg-/liberasurecode,cedricde/liberasurecode,tsg-/liberasurecode